The correct postsynaptic organization of cholinergic proteins at the neuromuscular junction requires the initiation and maintenance of functional innervation. The molecular mechanisms by which the genes encoding these proteins are regulated are largely unknown. The long range goal of this project is to determine how innervation controls the synthesis and expression of one member of the cholinergic synapse. acetylcholinesterase (AChE). AChE comprises a complex family of oligomeric proteins that differ structurally and in their association with cellular and extracellular compartments. Little is known regarding how the diversity of these proteins is generated. As a first step in understanding the mechanisms regulating the generation of the multiple forms of AChE we have chosen to study the genetic basis contributing to the diversity. This will include determining the structural nature of the transcripts and gene(s) for AChE and associating the types of mRNA transcripts with the molecular forms of the enzyme generated by the cell. These basic studies will then be applied in examining how innervation influences the transcriptional and posttranscriptional control of AChE expression and localization. It is likely that the nerve acts to regulate the local activity of synaptic proteins through its influence on synapse associated nuclei. This is a major hypothesis which we will examine using AChE as the candidate cholinergic marker. This project will use in vitro muscle-nerve cocultures and in vivo studies of denervated and innervated muscle to determine how nervous input controls AChE expression.